Method of designing a custom propeller

ABSTRACT

A method of designing a custom boat propeller with optimized geometry for a boat and motor combination based upon a user generated performance data set.

PRIORITY

The present invention claims the benefit of U.S. Provisional application 61/820,163 filed May 6, 2013.

FIELD OF THE INVENTION

The present invention deals with designing and selecting a custom boat propeller with optimized geometry for a boat and motor combination.

BACKGROUND OF THE INVENTION

Propellers are designed to operate at a particular rotational speed under full propulsive power. An improperly selected propeller can result in that rotational speed being reached at a lower power level. The operating speed of the propulsion unit has been reached, but it is not generating all of its available torque (power=torque*speed), and thus the boat is not able to go as fast. The major problem with a mismatched propeller and a boat and motor is that the motor is unable to use all of its available power.

One way to improve the performance of a propeller with a particular boat and motor is to increase the propeller efficiency. Propeller efficiency can be expressed as (propeller thrust*boat velocity) divided by (torque generated at the propeller shaft*propeller shaft rotational speed). However, while efficiency can be optimized at one particular boat speed, it will be suboptimal at all other speeds. For this reason it is critically important to know how the user is operating the boat (essentially a time history of their speed) so that the propeller can be optimized for that specific usage pattern. The benefits of higher efficiency include higher boat speed capability (more power available to overcome hull resistance) and increased range (a larger percentage of energy is being used to propel the boat).

The ultimate solution is to properly match a propeller with a specific boat and motor combination. However, propellers are not always optimized to a boat and motor and the user performance profile. And presently there is no technology available that allows users to generate custom propeller geometry and optimize a propeller for the specific boat and motor combination. Therefore, there is a need for properly designing or selecting the appropriate propeller geometries allowing users to get the highest efficiency and performance from their hull and motor combination.

SUMMARY OF THE INVENTION

The present invention solves the aforementioned propeller selection problem and provides a method of designing a custom boat propeller with optimized geometry for a boat and motor combination based upon a user generated performance data set. Specifically, the present invention provides selecting an available stock propeller for the boat and motor combination; operating the boat for a period of time and generating usage and performance data; collecting the motor, boat and propeller performance data during boat operation; and calculating custom propeller geometry based upon the motor and boat performance data.

The resulting custom propeller geometry can be used to fabricate a new propeller based upon the data Alternatively, the data and custom geometry can be used for selecting a more suitable propeller for the boat and motor combination from an array of available propellers.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is a novel method enabling users to get a custom propeller tuned for their exact boat or hull and motor combination. Currently boaters are only able to test their propeller performance by a sequence of guess and check cycles. The present invention allows the user to gather data of hull and motor performance by operating the watercraft and collecting performance data during normal operation. This data is then used to generate a custom propeller design based upon the users actual use and desired functionality.

The method of the present invention for generating unique propeller geometries allows users to get the highest efficiency out of their hull and motor combination. The present invention uses a device to gather system data during normal operation. One object of the present invention is to send system data to remote location for analysis by custom algorithm. The user is able to specify operating demands to further customize propeller geometry.

Preferably the present invention is designed to work with and gather data from any electric drivetrain system or electric outboard motors, such as those provided by Pure Watercraft, Inc. of Seattle, Wash. However, the present invention contemplates the use with all drivetrain systems including an outboard motor, inboard/outboard motor and inboard motor depending on the ability to gather the necessary data from other motor systems. With the ability to extract system data from other motor systems, propeller design can be enabled for many other suppliers, electric or internal combustion powered.

The device for gathering performance data can be incorporated into the boat design and manufacture or added later. The data-gathering device comprises at least one selected from the group consisting of one or more internal sensors, one or more external sensors and one or more global positioning devices. The present invention gathers data including engine/motor torque/power vs. speed to determine the drag profiles of the boat hull. The drag profiles in combination with the motor/engine torque/power profile are then used to generate custom propeller geometry based upon the users specified demands. The custom propeller can then be manufactured or selected from available propeller designs and sent to the user.

It is an object of the present invention to provide a method of designing a custom boat propeller with optimized geometry for a boat and motor combination based upon a user generated performance data set comprising selecting an available stock propeller for the boat and motor combination; operating the boat and generating usage and performance data; collecting the motor, boat and propeller performance data during boat operation; and calculating custom propeller geometry based upon the motor and boat performance data.

In addition to motor and boat performance data, another object of the present invention comprises determining a user performance profile from actual usage and incorporating the user performance profile into the custom propeller design. The invention also contemplates incorporating user-desired performance the custom propeller design.

Optimized propeller selection is essential for all marine motors including outboard motors. An outboard motor is portable and can be used with a variety of different boats and hull designs. Each hull has a unique resistance vs. speed relationship, and it is essential to use a customized propeller for the most efficient use of the motor and boat combination. Initial propeller selection will be an educated guess, which is the typical practice. The initial propeller choice is often suboptimal and the historical process for choosing a better propeller for the application is very unscientific as it involves using generic rules of thumb for deciding which propeller design would be a better choice. The present invention adds tremendous value, by using actual performance data collected from the powertrain to implicitly determine the resistance vs. speed relationship of the hull. By using that data coupled with a representative history of boat speed vs. time (usage profile) an optimal propeller can be designed or selected from the best available propeller for that boat and motor combination.

Most modern propellers are variable pitch, including the ones designed using the present invention. Most outboards are designed for a specific propeller diameter (the circumscribed circle tangent to the outer tips of the blades). Therefore, diameter will not be one of the parameters that changes based on user specific data. All other geometry parameters known in the art can be optimized, including the number of blades on the propeller.

Once the propeller geometry is optimized, the custom propeller can be manufactured by any available means. While traditional methods of propeller design and production rely on high volumes to reduce cost, new production methods including 3D printing and investment casting allow cheaper production of structural parts. The present invention is well suited to take advantage of this growing area of technology. As the 3D printing technology improves and the ability to manufacture one propeller at a time is facilitated, the costs of creating custom propellers will decrease.

An alternative option for customizing a propeller for a specific boat and motor combination is to collect the necessary boat performance data and then select a more suitable propeller based upon the motor and boat performance data. Another object of the present invention contemplates developing a set of propellers and maintaining a database of specific propeller geometries for particular boat and motor combinations.

It is an object of the present invention to collect the necessary boat and motor performance data by any means available for designing and selecting a custom propeller. The operational performance data for a specific boat and motor combination include the following measurements taken during operation; boat velocity, motor output rotational speed (RPM), input electrical current to the motor/inverter, and input electrical voltage to the motor/inverter. The performance data can then be used with existing propeller design parameters for designing the new propeller geometry.

All of the data necessary for designing a custom boat propeller with optimized geometry for a boat and motor combination is available from an appropriately equipped outboard, with the exception of boat velocity. However, most mobile devices have a GPS receiver, which can be used to calculate velocity. With mobile connectivity between the outboard and a mobile device, a preferred method of data collection of the present invention involves a mobile app collecting data directly from the outboard, time syncing it with the GPS velocity data, storing it on the mobile device, and transmitting it to a cloud server from the mobile device.

In another embodiment, a GPS receiver can be included in the outboard motor so that it can determine the boat velocity. With the positioning of the boat and the performance of the boat and motor combination, the data can be time synced and stored locally within the outboard. The data can then be wirelessly transmitted directly to a mobile device (which then uploads to a cloud server), or it could connect to a local wireless network and transmit the data directly to a cloud server. Alternatively, the data can be loaded onto a flash media device (for example, a USB port on the outboard), which the user could later upload to a cloud server using an internet connected device, or the user could send by email or through regular mail.

The present invention is further exemplified by the following claims. 

We claim:
 1. A method of designing a custom boat propeller with optimized geometry for a boat and motor combination based upon a user generated performance data set comprising: a. Selecting an available stock propeller for the boat and motor combination; b. Operating the boat and generating usage and performance data; c. Collecting the motor, boat and propeller performance data during boat operation; and d. Calculating custom propeller geometry based upon the motor and boat performance data.
 2. The method of claim 1 further comprising determining a user performance profile from actual usage and incorporating the user performance profile into the custom propeller design.
 3. The method of claim 1 further comprising incorporating user desired performance into the custom propeller design.
 4. The method of claim 1 wherein the motor and boat data collected is at least one selected from the group consisting of boat velocity, motor rotational speed, motor torque, thrust, propeller geometry, input electrical current to the motor/inverter and input electrical voltage to the motor/inverter.
 5. The method of claim 1 wherein the motor is at least one selected from the group consisting of outboard motor, inboard/outboard motor and inboard motor.
 6. The method of claim 1 further comprising fabricating the custom boat propeller based upon the motor and boat performance data.
 7. The method of claim 6 further comprising fabricating the propeller using a 3D printer.
 8. The method of claim 1 wherein a boat operator uploads the performance data.
 9. The method of claim 1 further comprising using a data-gathering device on the boat for gathering performance data.
 10. The method of claim 9 wherein the data-gathering device comprises at least one selected from the group consisting of one or more internal sensors, one or more external sensor and one or more global positioning devices.
 11. The method of claim 10 further comprising accumulating global positioning data using at least one portable mobile device selected from the group consisting of a cell phone, tablet and laptop.
 12. The method of claim 11 further comprising using a mobile application for combining the global positioning data with boat and motor performance.
 13. The method of claim 9 where in the gathered data is uploaded to a portable data storage device.
 14. The method of claim 9 wherein the gathered data is transmitted wirelessly to a remote location.
 15. A method of designing a custom boat propeller with optimized geometry for a boat and motor combination based upon a user generated performance data set comprising: a. Selecting an available stock propeller for the boat and motor combination; b. Operating the boat and generating usage and performance data; c. Collecting the motor, boat and propeller performance data during boat operation; and d. Selecting a more suitable propeller based upon the motor and boat performance data.
 16. A method of designing a custom boat propeller for a boat and motor combination comprising: a. Gathering motor and boat performance data during operation; b. Calculating custom propeller geometry based upon the motor and boat performance data; and c. Designing the propeller based upon the motor or and boat performance. 